S1057 Efficacy and Safety of Guselkumab Maintenance Therapy Among Guselkumab Induction Week 24 Clinical Responders: Results From the Phase 3 QUASAR Maintenance Study

Introduction: The QUASAR program (NCT04033445) evaluated guselkumab (GUS), a dual-acting interleukin-23p19 subunit inhibitor, in patients (pts) with moderately to severely active ulcerative colitis (UC). Induction Week 12 (Week I-12) nonresponders to intravenous (IV) GUS received subcutaneous (SC) GUS through Week I-24.1 Week I-24 responders were eligible for maintenance therapy. Here, we present the efficacy and safety of maintenance SC GUS among GUS Week I-24 responders. Methods: Pts who were not in clinical response (definition in Table 1) at Week I-12 after IV GUS 200 mg or 400 mg received SC GUS 200 mg at Weeks I-12, I-16, and I-20. Those who were in clinical response at Week I-24 received SC GUS 200 mg every 4 weeks during the maintenance study in a blinded fashion and were evaluated as part of the nonrandomized study population. Clinical, symptomatic, endoscopic, histologic, and patient-reported outcome measures at maintenance Week 44 (Week M-44) and safety throughout the maintenance study are reported for GUS Week I-24 responders. Results: Overall, 123 of 203 (60.6%) Week I-12 nonresponders to IV GUS achieved clinical response at Week I-24 and entered the maintenance study phase. Induction baseline characteristics of GUS Week I-24 responders were: 74.8% had severe disease (modified Mayo score 7-9), 77.2% had a Mayo endoscopy subscore of 3, median CRP was 5.0 mg/L (upper limit of normal, 3 mg/L), and 59.3% had a history of documented inadequate response or intolerance to biologic, or JAK inhibitor therapy for UC. At Week M-44, 67.5% of the pts maintained clinical response and 30.1% were in clinical remission. Additional efficacy outcomes are shown in Table 1. The proportion of GUS Week I-24 responders in symptomatic remission (defined as a stool frequency subscore of 0 or 1 and not increased from induction baseline, and a rectal bleeding subscore of 0) at maintenance baseline (58.5%) was sustained through Week M-44 (56.9%) (Figure 1). Adverse events (AEs) were reported for 78.0% of GUS Week I-24 responders, serious AEs for 5.7%, and serious infections for 1.6%. No opportunistic infections or deaths occurred. No new safety concerns were identified. Conclusion: In this refractory population of GUS Week I-24 responders, maintenance treatment with GUS provided clinical benefit across a range of clinically relevant efficacy endpoints. Safety results were consistent with the overall population and safety profile of GUS in its approved indications.Figure 1.: Symptomatic Remission (a) Through Maintenance Week 44 for GUS Induction Week 24 Clinical Responders. CI-confidence interval; GUS=guselkumab; every 4 weeks=every 4 weeks. a Symptomatic remission was defined as a stool frequency subscore of 0 or 1 and not increased from induction baseline, and a rectal bleeding subscore of 0. Table 1. - Efficacy Outcomes at Maintenance Week 44 for guselkumab Induction Week 12 Nonresponders Who Achieved Clinical Response (a) at Induction Week 24 GUS 200 mg SC every 4 weeksN=123 n (%) Clinical remissionb 37 (30.1) Endoscopic improvementc 44 (35.8) Corticosteroid-free clinical remissiond 37 (30.1) Maintenance of clinical responsee 83 (67.5) Histologic-endoscopic muscosal improvementf 34 (27.6) IBDQ remissiong 67 (54.5) Fatigue responseh 49 (39.8) Maintenance of clinical remissioni, N=20 10 (50.0) Endoscopic remissionj 21 (17.1) GUS=guselkumab; IBDQ=Inflammatory Bowel Disease Questionnaire; PROMIS=Patient-Reported Outcomes Measurement Information System; pts=patients; every 4 weeks=every 4 weeks; SC=subcutaneous; Week M-44=maintenance Week 44.Note: Includes only pts with modified Mayo score 5-9 at induction baseline.aClinical response was defined as a decrease from induction baseline in the modified Mayo score by ≥30% and ≥2 points, with either a ≥1-point decrease from induction baseline in the rectal bleeding subscore or a rectal bleeding subscore of 0 or 1.bClinical remission was defined as a Mayo stool frequency subscore of 0 or 1 and not increased from induction baseline, a Mayo rectal bleeding subscore of 0, and a Mayo endoscopic subscore of 0 or 1 with no friability present on the endoscopy.cEndoscopic improvement was defined as a Mayo endoscopic subscore of 0 or 1 with no friability present on the endoscopy.dCorticosteroid-free clinical remission was defined as clinical remission at Week M-44 without any use of corticosteroids for ≥8 weeks prior to Week M-44.eMaintenance of clinical response was defined as clinical response at Week M-44 among pts in clinical response at maintenance baseline.fHistologic-endoscopic muscosal improvement was defined as achieving a combination of histologic improvement (defined as neutrophil infiltration in < 5% of crypts, no crypt destruction, and no erosions, ulcerations or granulation tissue according to the Geboes grading system [i.e., Geboes score ≤3.1]) and endoscopic improvement.gIBDQ remission was defined as a total IBDQ score ≥170.hFatigue response was defined as a ≥7-point improvement from induction baseline in the PROMIS Fatigue Short Form 7a.iMaintenance of clinical remission was defined as clinical remission at Week M-44 among pts in clinical remission at maintenance baseline.jEndoscopic remission (normalization) was defined as a Mayo endoscopic subscore of 0.

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